ZX Appeal

SEPT/88 °

Vancouver sinclair
Users g OHF

NeXT meeTiny

ZXAppeal is a monthly

newsletter put out by the

Vancouver Sinclair Users Group.

For more information on the

group and ZXAppeal see the backcover.

THIS ISSUE. ii we acien

Summer is over and now it's back to
the grind. Hope you had a good
vacation. The cooler weather should
come shortly and with it more time
spent indoors. And that means more
time spent computing!

Not much in the way of submissions
this month other than a couple of
things from Harvey: another ‘Playing
with', and his thoughts on the recent
'Do' in Portland. ( I'm still not sure if
he liked it or not.) I"ve- managed to
steal an item you might find of interest:
a recent write-up on Clive in a new
'PC' type mag. This one is a little more
positive in its viewpoint. Part II of the
‘Cassette Connection'- continued from
Part 1 last month, is reprinted from
SyncWare News with Fred's
permission. And some other stuff 1
hope you'll find of interest.

By the way, the April issue included an
article by Harvey on Modapters for the
QL. Well, the circuit diagram was left
out by mistake. This error was not
noticed by any reader until the article
was reprinted in another newsletter.
They didn't notice it either but 1 did.
When I read their newsletter and saw
the diagram missing, 1 checked back in
the April issue to find that I'd left it
out also! Does anyone read this stuff???

ARA a ae Oe a a o a a EE EE EEE

Bits & Pieces ini dni dra

... Keeps on Tickin"...another report
has come in saying ZX81s are still being

used to manufacture dedicated 2

industrial controllers. This time it is a
Swiss firm - adding an LCD display and
I/O interface to the "door-stop".

...the paper library now has a copy of
each of the Sam's books
"ComputerFacts" technical and repair
manual for both the 1000 and the 2068.
If you need to know any of the 'specs'
of either machine, these publications
will have it.

...the PCCFA will be holding the next
Computer Fair and Swap Meet/Flea
market on Saturday, October 1. The
group will again be holding down a
couple of tables to show-off our
machines and let the world know
we're still around. All members
wanting to 'man' the tables can put
their name on the list at the Sept
meeting. Everyone should try to drop
in to this Fair as some great bargains
can be found.

...your Editor is now the owner of the
QL previously owned by the man who
oversaw the development of the QL for
Sinclair. Nigel Searle sold me an
original ZX80 kit as well as his personal
QL, complete with software, p/supply,
& manual, for $50.00. He paid $20.00
postage to mail the QL to me!

...aS you will read within, Harvey T. has
succumbed to the hacker's version of
'threefootitis'. This is the affliction
that strikes boat owners every spring -
they start drooling over boats about 3
feet longer than the one they presently
own. Harvey bought an Amiga. He
advises he will still work/play with his
QL and even bought some additional
RAM for it from Sharp's at the recent
‘Fair in Portland. Too bad the 3086

didn't see the light of day.

„next
meeting

A GREAT NORTHWEST SINCLAIR
FEST TRIP REPORT

-by Harvey Taylor

| wasn't going to go. | had made up my mind |
was too disappointed last year, it was too far
away, | didn't want to go to the states again.
Then at the last minute Wilf phoned & bang. In
an instant, | changed my mind.

Well, | have good news & | have bad news. The
good news is that only the fanatics are left 8
the bad news is that only the fanatics are left.
You could characterize the fest as more of a
wake & catch one of the predominant feelings
there. Some dry statistics tell the tale...
Expected attendees 300-600. Actual attendees
100-150. There were a lot of “Why aren't there
more users, more club members --- Where did
everybody go?” questions. And the answers are
fairly clear, if you care to look. They went back
to golf/cars/girls/the latest craze or they
moved on to Mac/Amiga/ST/IBM/robots/ or
whatever non-orphan.

A group like a computer club exists in one
sense as a group self-education process. At the
beginning, we were all lost & maybe somebody
in the group had come across your problem &
knew how to fix it or avoid it. We all taught

each other our neat tricks. Some passed through
the group quickly. Others stuck around and made
friends. There are those few who really are
attracted by design elegance, by facing the
question --- just how much can you pack into
8K of ROM. Fanatics.

As for the Festival itself..there were a few
high points - the evening free-for-all when
somebody asked how many people were
seriously interested in the 266 & two dealers
held up their hands. Also during the
free-for-all, there was a spark of life when
plans were made to try to interest the SNUG
(Sinclair National User's Group) [Americans

have no inkling why they might went to call
this proposed organization a North American
User's Group] group in a BBS based continental

newsletter.

The other interesting part of the Fest for me
was just in the people | met. It is a treat to
meet £ talk with other knowledgeable QL'ers --
to find out what other people are developing &
wrestling with. These personal contacts are the
ultimate rationale for such Festivals.

PLAYING WITH ELECTRICITY
- Harvey Taylor

_. Tucked away in a description of the QL hardware in the
Technical Guide is mention of the fact that bit 7 of the
Display Control Register “can be used to switch the base of
screen memory from $20000 to $28000”. Hmmm, interesting |
thought and went on to more pressing concerns.

Recently, | went back to investigate the dual screen
display. There is a discussion & program dealing with it in
Adrian Dickens “QL Advanced User Guide”. The news is it is
real; but flawed. First a quick overview of the QL memory
map.

256K 00040000 Top of On Board RAM
192K 00030000 Top of Screen!
Top of Common Heap
Base of Common Heap
00028480 Top of Sys_Var
160K 00028000 System Variables & Base of Screen1
00027FFF Top of Screend
128K 00020000 Base of Screend

The immediate problem with the second Screen is the fact
that the System Variables are locked into $28000 which is the
base of Screen!. This means that if you simply flick the bit
which controls the base of the display, you will get a bunch
of garbage onthe top of your screen. The garbage is the
video representation of the System Variables.

You can take a look at this effect with the following
short Superbasic Procedure.

100 REMark switch in Screen 2

110:

120 DEFine PROCedure SWITCH

130 SY_MCSTA=163892 : REMark $28034

135 DC_REG =98403 : REMark $18063

140 DCRZSTATUS=PEEK(SY_MCSTA)

150 DCR_STATUS=DCR_STATUS ” 128: REMark toggle bit 7
160 POKE SV_MCSTA,DCR_ZSTATUS : REMark tell Sys_Var
170 POKE DC_REG,DCR_STATUS : REMark tell hardware
180 END DEFine SWITCH

190:

This is interesting, but useless. To make a useable
display, one has to be a little trickier. One of the neat
things about the QL is that QDOS is extensible. In
particular, one can link in tasks for the QL to perform efter
each interrupt. There is a Level 2 Interrupt (called a Frame
Interrupt) on the QL every 1/60 second; which is related to
the Vertical Sync signal.

What we need to do is Link in a short Task which checks
what screen we are displaying; then if we are displaying

ScreenO, do nothing, while if we are displaying Screen1, wait -H~

until the display has passed the SK or so of System Variables
then switch in Screen}.

The assembly language code to do this is listed below
in the file DualScr_esm. Once you have this code installed,
you will run into the next problem. There is no support in
QDOS for writing to Screen1. It is evident that in the
development of the QL, this was a matter of some debate,
because in the SCR/CON Channel Definition Block (CD_BIk),
there is on entry (SD_SCRB) Base address of screen. The
unfortunate fact is that the SCR/CON device driver does not
use this variable. Instead the base address ($20000) is
hardcoded into the driver. This was no doubt done in concert
with the decision to tie the System_Variables at $28000.

As the QL is at present, if the driver did use the
CD_BIk variable, clearing the screen would erase all the
System_Variables; so it is just as well that it is not
implemented!

What's to do? It seemed to me that the simplest method

- to use would be to simply copy Screen0 into the useable part

of Screen1. The Superbasic extension SCOPY performs this
task. | wanted a Clear Screen! capability as well, so | added
the PROCedure SCLR. This procedure expects one parameter
which is used to colour Screen!. The video ram of the QL
display is arranged thus:

Mode 4
Even Byte : Odd Byte
76543210 76543210 - Bits

GGGGGGGG : RRRRRRRR G - Green
R - Red

Mode 8 F - Flash

Even Byte : Odd Byte B - Blue

76543210 76543210 -Bits
GFGFGFGF : RBRBRBRB

Passing SCLR the parameter 0, will point the screen
black. You can play with other parameters to see the effect
of setting various bits. If you use 65280 for Green, the
interpreter returns an overflow error; but -256 works fine.
255 paints the screen red.

The procedure SCRO turns off the Auto-Toggle and gives
you the default display, ie. ScreenO. The procedure SCR1
turns off the Auto-Toggle and gives you Screen!. The
procedure SCRA turns on the Auto-Toggle; ie. switch between
the two screen using <CTRL><F5>.

The function SCRNUM tells you which screen is currently
being displayed, O or 1. The function SWHERE tell you the
base of the Common Heap Memory reserved by the initialization
code.

There are some proviso's with this code. It should be
initialized fom a boot: in particular before a directory of
a second device is done. This is because we went Screen! to
begin as close to the Base of the Common Heap as possible. If
you do a directory of another device before initializing;

QDOS reserves some common heap as a Channel Definition Block
and a Physical Definition Block. This will show up as a white
band similar to what SWITCH produces.

Related to this situation is the value of the Timeout
value used to wait before switching Screen! on. See the
comments in the _asm file. =
The other proviso, is that the dividing line where
Screen! switches in is not stable. The easiest way to handle
this problem, is to put a black border over the region
similar to the PROCedure SDEMO below.
The first SBasic program below creates a file DSCR_ext
which is used by the second the SBasic program SDEMO.
>eof

100 REMark PLAY WITH SCREEN UTIL
110:

120 LAYOUT

130 INIT

140 DEMO

150 STOP

160:

170 DEFine PROCedure DEMO
160 PAPER 0: CLS

190 PICTURE

200 PAPER 4

210 AT 0,0: PRINT ‘SCREEN 1°
220, SCOPYr230 SCRI

240 CLS

250 SCRO

260 SCRA

270 LISTTO 260

280 AT 0,0: PRINT ‘SCREEN 0°
290 PRINT*0/'USE <CTRL><F5> TO TOGGLE SCREENS’
300 END DEFine DEMO

310:

320 DEFine PROCedure PICTURE

330 FOR M=0 TO PI STEP .25: FOR N=0 TO 105 STEP 15 : INK (RND(2,6)):

CIRCLE 200, 128,N,.5,M: END FOR N : END FOR M
340 INK7
350 END DEFine PICTURE
360:
370 DEFine PROCedure INIT
380 nem$="SCR2_ext'
390 dev$="fipi_'
400 LBYTES dev$ & nam$,RESPR(S 12)
410 PRINT'Loaded'
420 CALL RESPR(O)
430 PRINT'Initialized'
440 END DEFine INIT
450:
- 460 DEFine PROCedure LAYOUT
470 WINDOW*0,512,64,0,0 : BORDER *0,10,0
480 WINDOW*1,512,192,0,64 : BORDER *1,10,0
490 WINDOW*2,512,192,0,64 : BORDER *2,10,0
500 PAPER*2,4: INK*2,0
510 PAPER*1,4: INK*1,7
520 PAPER*0,2: INK*0,7
530 SCALE 256,0,0: MODE 4
540 END DEFine LAYOUT

100 REMark Create SCR2_EXT file
110:

120 DLOAD
130 DSAVE
140 STOP

“> TO":

160 DEFine PROCedure DSAVE
170 REMark Save memory to file
160 nam$="SCR2_ext’

190 dev$="flpi_

200 SBYTES dev$ & nam$,RESPR(0),406
210 END DEFine DSAVE

220:

230 DEFine PROCedure DLOAD

240 REMark writes DATA to memory & inits PROC & FUNC
250 addr=RESPR(512)

260 RESTORE 400

270 REPeat loop

280 READ x: IF x=-1: EXIT loop

290 POKE addr,x

300 addr=addr+ 1

310 END REPeat loop

320 PRINT*O/Loaded '

330 CALL RESPR(O)

340 PRINT*0/Initialized'

350 END DEFine DLOAD

360:

370 REMark SCR2_ext code for 2 screens utility
380 REMark SCLR,SCOPY,SCRO,SCR1,SCRA; SCRNUM,SWHERE
390 REMark

400 DATA 67,250,0,70,52,120,1,16

410 DATA 78,146,116,0,34,60,0,3

420 DATA 0,0,6

5,249,0,2,128,0

430 DATA 32,40,0,8,65,240,8,0

440 DATA 146,136,47,1,112,24,78,65
450 DATA 34,31,74,128,102,24,67,250
460 DATA 1,16,34,136,67,250,1,24

470 DATA 65,250,1,12,112,28,33,73
480 DATA 0,4,78,65,112,0,78,117

490 DATA 0,5,0,144,4,83,67,82

500 DATA 65,0,0,144,4,83,67,82

510 DATA 48,0,0,144,4,83,67,82

520 DATA 49,0,0,88,5,83,67,79

530 DATA 80,89,0,34,4,83,67,76

540 DATA 82,0,0,0,0,2,0,174

550 DATA 6,83,67,82,78,85,77,0

560 DATA 0,116,6,83,87,72,69,82

570 DATA 69,0,0,0,52,120,1,18

580 DATA 76,146,74,128,102,8,12,67
590 DATA 0,1,103,4,112,241,78,117
600 DATA 48,54,152,0,65,250,0,154
610 DATA 32,80,67,249,0,3,0,0

620 DATA 48,192,177,201,101,250,96,0
630 DATA 0,132,67,249,0,3,0,0

640 DATA 32,9,65,250,0,124,32,80

-S~

650 DATA 144,136,83,64,69,249,0,2
660 DATA 128,0,19,34,81,200,255,252
670 DATA 96,98,67,250,0,104,80,209
680 DATA 96,90,67,250,0,96,66,81
690 DATA 96,82,67,250,0,88,50,188
700 DATA 0,255,96,72,67,250,0,74
710 DATA 34,17,34,110,0,88,93,73
720 DATA 45,73,0,88,66,118,152,0
730 DATA 74,129,103,16,52,60,8,32
740 DATA 83,66,227,129,104,250,226,145
750 DATA 61,130,152,0,45,129,152,2
760 DATA 120,2,96,24,114,1,194,58
770 DATA 0,29,34,110,0,88,85,73
780 DATA 45,73,0,88,61,129,152,0
790 DATA 56,60,0,3,112,0,78,117
800 DATA 0,0,0,0,0,0,0,0

810 DATA 0,0,0,0,0,0,18,46

820 DATA 0,52,19,193,0,1,128,99
830 DATA 74,43,0,7,103,36,74,174
840 DATA 0,152,102,50,74,174,0,156
850 DATA 102,44,74,46,0,238,102,38
860 DATA 48,60,6,44,81,200,255,254
870 DATA 8,193,0,7,19,193,0,1

880 DATA 128,99,74,43,0,6,103,14
890 DATA 74,46,0,51,103,8,81,238
900 DATA 0,51,70,43,0,7,78,117,-1
910:

Disk Droppings
by
Greg Lloyd

The latest offering from Larken Electronics is a 256K

RAM-DISK for the 2068. It gives the owner up to 2561
of Hon-Yolatile Static Ram (SRAM). This is battery
backed storage of up to 256K of programs and data. It
can be used in conbination with the DSK 488 disk
interface and 4 disks or on its own with the LEIDOS
cartridge. It will also AUTOSTART to load and run a
program on power up.

The board used for the RAM-DISK is roughly the size
of the DSK 466 - 4 x 2 inches and piggy-backs to the
your disk interface or the expansion port on the 2068.
It is fully through ported so other periferals can be
hung behind. My 2656 nodem and 2049 printer worked
just fine. The order of installation does not seen to
matter. I used the DSK 408 interface then the RAM-DISK
personally.

To default to the RAM-DISK you just have to press the
[ J J key and [ ENTER ] on power up. If you have saved
a startup aenu or any other application it loads and
runs immediately. The tine involved is about one
second. If you have used the 1/S Command Cartridge
System to run Crazy Bugs or States and Capitals you
will see the advantage over tape and disk. The added
feature is that you can save and change data on the
RAM-DISK and it will still be there after you turn the
sachine off. This all happens in a blink of an eye. No

Reprinted from the May/June issue of Sinc-Link - the

N/L of the Toronto T/S Users Group

whirring, clicking, popping, grinding, crunching,
gorching or glitching and no red leds flashing. You
can also use the command PRINT $4: GOTO 4 if you are
already powered up. The LIDOS software sees the RAN-
DISK as the fifth possible drive. All in all, a new
and nost unusual experience. Larken Electronics has
not only brought 2068 disk users a new standard of
compatibility but now a new meaning to the phrase
“Silent Service”.

Sir Clive’s latest creation the 1-88 (bearing the
Cambridge Computer name and a huge price tag in ay
huable opinion), uses the same principal to store and
operate. Solid state memory is certainly faster, nore
robust and has fewer moving parts than any disk systea
I have seen. I think it is the most sensible way to
go, barring the resurrection of those beloved micro-
drives. My system has 128 of SRAM on board. This gave
ae enough storage to be useful and no concern about
saking the mortgage payments.

The bare board unassembled and without memory is
priced at $15. The assembled board without memory is
available for $68. A LIDOS cartridge and software
upgrade is necessary to run this option. The setup
could be used as the only source of storage if
desired. It does aake a neat solution to those of you
who wish not to go for a disk drive. All other
functions are still available so you could save to
tape for permanent storage and backup.

Larry Kenney the wizard behind the system, has
developed a back-ground print spooler. This feature
allows Tasword files to be printed while another
progras is running. This is another plus to the
system, the creator is using and developing further
enhancerents to the machine. And you thought you had
an orphan computer. Sorry to disappoint you.

SRAM chips needed for the RAM-DISK are 43256LP fron
NEC or 62256LP from other manufacturers. The latter
are priced $26.48 (Can.) at Active Components. The
speed of these should be 128 or 158 nanosecond. The LP
stands for low power and unless you have an unlimited
supply of batteries its recozmended you use the LP
version. Larken Electronics has some SRAM chips avail-
able for less and Computer Shopper has thea advertised
from $11 to $13 (0.S.) if you want to wait. Price is
now volatile in the non-volatile resory narket.

So if you have a DSK 488 from Larken and want to get
the latest goody or if you don’t have a disk and want
sone of the benefits, get in touch with your checkbook
and order the RAM-DISK. I find it the best thing I
ever did for ay 2068 system. To quote from the movie,
“I feel the need ...-the need for SPEED". You don't
need to join the Navy or buy and F-14, get a RAM-DISK
from Larken and go supersonic. GBL 880428.

2068 CASSETTE CONNECTION

Part Il: Loading Tips

In the last issue, I recummended removal of a couple
capacitors in the SAVE circuitry of the TS2068. This _
provides a “brighter” save signal, which makes
subsequent loading more reliable. This is all that

is required to get many systems working "up to

spec," and makes the use of “fast-load” routines
possible, even practical. On further research,
however, I found that there can still be problems

with some systems involving the LOAD portion of the
computer-to-tape interface. In this article, I'll
discuss the load circuitry, and suggest a few minor
changes that you can make to improve reliability if
you're still having trouble.

Before I get on with this, I should mention that NOT
ALL. TS2068's ARE CREATED EQUAL. I had the oppor-
tunity to look at a 2068 recently acquired from
Games To Learn By (GTLB), and found that the small
capacitors directly across the MIC and EAR jacks on
the underside of the board were absent on this unit.
Also, the two series 1N4148 diodes CR25 and CR26
(discussed later) were bridged with a single
identical unit, Furthermore, there are appreciable
discrepancies between the Timex schematic and the
actual hardware. For example, the SAVE circuit shows
yet another capacitor across the MIC output (C72)
which is not even marked on the board on either unit
I've seen. There are also various other capacitors

and wires floating around which look suspiciously
like “tack-ons."

To complicate matters further, it appears that there
are at least two discrete board patterns in
existence, with different parts callouts for the
same components. These alternate parts callouts are
shown on the schematic in parentheses with a "-3A"
suffix, For example, capacitors C7 and C8 in the
LOAD circuitry (discussed later) are C6 and C7,
respectively, in the "-3A" version. Both of the
boards I've seen have a "-03D" suffix in the number
under the "TIMEX 2000" legend and both corresponded
with the "-3A" variation on the schematic, so
presumably any board designated "-3A" or greater
will follow the alternate part numbers on the
schematic. The bottom line is that what you read
here and elsewhere about the 2068 hardware may or
may not jive exactly with your machine.

FIGURE 1.

Insert Figure 2 here

EAR JACK

-001 uFd.

2

c73
120 pFd.

f the author.

10n O

h permiss

lews wit

T
N

Reprinted from SyncWare N

Now, let's see what we can do to make 1t easier to
“get loaded" on the 2068. The applicable portion of
the schematic is reproduced here in Figure 1. As in
the case of the MIC jack, there is at least one
capacitor (C73) directly across the EAR jack. Again,
this (or these) were presumably included to help
reduce radio and TY interference. It seems that
Timex's philosophy was, “if some capacitors do some
good, then more will do more good." Unlike the caps
across the MIC port, however, the one or ones on the
EAR jack have a negligible effect on the tape signal
itself. This is because the impedance looking into
the MIC input of the recorder is several magnitudes
higher (typically about 50,000 ohms) than the
impedance of the EAR output (around 10 ohms). As a
result, there Is nothing to be gained by removing
these capacitors, so you might as well leave it in!
Who knows, they might even help reduce interference
slightly.

Looking further into
resistor (R11,
jack as well. Again, this is so

the schematic, we find a
1000 ohms) in parallel with the EAR
much greater than

the output impedance of the tape recorder EAR jack
that it has no significant effect on the tape
signal. It was probably included to provide the DC

return required by some recorders. After that is a
little network consisting of two resistors R12 and
R73, two caps C8 (C7-3A) and C7 (C6-3A), and two
diodes (CR25 and CR26). This is essentially a “diode
clamp" circuit, which shifts the signal from, say -3

to +3 volts, to about -4 to +1,2 volts. Also, it
provides a low-frequency (LF) corner of about 230
Hz., and a high frequency (HF) corner near 23 kHz.

My reason for digging into this was that I sometimes
couldn't get some tapes to load, even at maximum
volume setting on my 6 volt TS2020 or Minisette
IX's. A quick measurement showed that my line
voltage was somewhat low, around 110 volts. My
present home-sweet-home has long secondary power
lines and electric heat; I found that some tapes
would load ok with the heaters unplugged, but
wouldn't "take" if the AC line voltage dropped below
the rated 120 VAC. A colleague reported similar
problems, especially when trying to use a fast-load
program to speed up the tape processes. If you're
having similar border-line sensitivity problems with
tape loading, the following modification may quite
possibly handle it.

2.2K (add)

-7

+5V

R72 390K
C7 (C6-3A)

ol uFd.
PIN 15

SCLD CHIP
(tape in)

R73 62K

C8 .001 uFd.
(C7-3A) =

(optional to remove)

2068 LOAD Circuit Mods

1: Open the 2068 by removing the seven screws and
disconnect the keyboard tall. (Thankfully, the
KB tail on the 2068 is considerably more
substantial than the ones on the ZX81/TS1000!)

2: Locate the 6800 ohm resistor, R12 (blue-grey-
red-gold). This is about 1 cm. below and
slightly to the left of the C10 capacitor you
removed last issue. Bridge this resistor with a
2200 ohm, 1/4 watt unit (red-red-red-gold).
This will make the mod easy to remove if it
doesn't do the trick for you. Alternately, you
may clip the 6800 ohm resistor and replace it
with an 1800 ohm unit. This increases
sensitivity, which in my case was enough to
allow loading tapes that wouldn't quite "take"
even at full blast. It also raises the LF
corner, making the system yet more immune to
low-frequency garbage.

3: I also removed capacitor C8 (C7-3A), even
though doing so is not strictly necessary; the
HF corner created by this cap ls high enough to
avold trouble with the standard tape routines.
However, it may conceivably get in the way if
you later use VOTEM or other V-F (voltage to
frequency) analog interfaces, or if you decide
to experiment with fast-load routines. Although
the 2068 (about 1500 baud)is a lot faster than
the ZX81 (at about 300 baud), a good tape
recorder will support even faster loading; up
to about 3500 baud, or 440 bytes per second.

4: Reconnect the KB tall, and set the board back
into the case. Test your modification. If
you're satisfied that you now have enough
sensitivity, screw the two case halves back
together,

This will handle many loading problems. Aside from
the comparatively low sensitivity of the 2068's load

ciecultry, there's not much for which it can be
faulted. Unlike the ZX81, the SCLD custom chip
apparently contains a comparator to square up the

FIGURE 2, +15 to 18 Volts
c3
INPUT FROM
EAR JACK ——
$ OUTPUT TO
> | R11 and R12
cı
R4A
R4B

signil. As a result, adding a comparator or Schmidt-
trigger conditioner probably won't have a noticeable
effect. However, if you have a tape recorder with a
6 volt supply, chances are you might still have
trouble with sensitivity. If so, here are a few
options:

l: You can use VOTEM to help out, but you'll need
to make a couple modifications. First, you'll
have to supply a 9-volt power source such as a
“transistor radio" type battery. Then, you'll
have to connect the function of R1 and RS to
+9Y instead of +5, to give you a larger output
swing. One caution, however; this modification
may make it unusable with the ZX81/TS1000, as
these prefer a lower tape signal voltage and
some of them balk if it's too high.

2: Get a recorder with a higher supply voltage,
e.g. 7.5 or 9 volt. This will allow a higher
output swing.

3: Replace your present 6Y AC adaptor with a 7.5
volt unit. These are available from Radio Shack
and other sources. Try to get it on the
condition that you can return it if it doesn't
do the job. The slightly increased supply
voltage will not harm well-designed recorders,
but may be just enough to push you “over the
hump." This option, if it works, is a lot
cheaper than buying a new deck.

You might experiment with the number of diodes In
the clamp. (Be warned! You are dealing directly with
the SCLD chip. DON'T BLOW IT!-ed.) This affects the
positive clamp level, at the rate of about .6 volts

per diode. As mentioned above, the units from GTLB
have the two diodes (CR25 and CR26) bridged with a
Single one. I tried this on mine, and found that it
actually seemed to make matters worse. I also tried
adding an extra diode in series, and found no
noticeable change. You might also try increasing C8
(C7-3A) to, say 0.22 uF., especially if you reduced
R12,

PARTS LIST - 2068 LOAD AMP

C1-C3 - luFd., 16V tantalum
C2 - 47 uFd., 6Y electrolytic
Q1 - general purpose audio transistor
2N3904, 2N4401, etc.
R1 - 910 Ohm 1/4 watt
R2 - 4700 Ohm, 1/4 watt
R3 - 470 Ohm, 1/4 watt
R4A - 100 Ohm, 1/4 watt
R4B - 33 Ohm, 1/4 watt >

1"x 1" perfboard, wire, solder, sticky foam.

** Por the convenience of those readers who would
rather not scout around for parts, I (Fred Nachbaur)
will wire up these boards, so that they will be
ready for you to install, for $6.00 each (add $3.00
for speedy mail service). You'll then only have to
cut one trace and make four wire connections.

..cont'd on pg.10

a U RO | z C E stolen from the Sept/88

O... a Profes-

sor Brainstorm-type eccentric British
inventor and most people will conjure
up something approaching bald, be-
spectacled Sir Clive Sinclair. Sir Clive
is the designer of such great leaps for-
ward as the first mass-produced electric
car (a dismal flop), the flat 2!/,-inch
TV screen (he beat the Japanese into
production with one), and a handful of
market-shattering personal computers
dubbed the ZX range, which are best
known in Europe. The ZXs are now
part of the ever-growing Amstrad em-
pire, to which Sir Clive sold the
venture.

Now ensconced among the academic
spires of Cambridge, a sleepy train ride
from London, Sir Clive probably got
the idea for his latest foray into com-
puters during
painfully boring
journeys to the
capital.

Sir Clive's
new brainchild
is called the
Cambridge Z88,
and your first
delightful im-
pression as you
take it from its
box is that it is
so light, some-
one must have
forgotten to put
the electronics
inside. Immedi-
ately you might
ask, “Where are
the disk drives?”
The fact is there
are none, which
starts a worry-
ing series of
thoughts along the lines of, “How am 1
going to get data to and from my desk-
top IBM-compatible PC?”

This gets to the heart of what the Z88

Eccentric British inventor Sir
Clive Sinclair can add a
notebook-sized computer to his
list of accomplishments.

By PETER WHITE

is really about—serious portability and
“no tears” translation into PC-DOS
machines, especially for WordStar us-
ers. Sir Clive clearly realized that the
only thing computer users on the move
need to do is input data in retrievable
form.

So he’s built a machine, based on the
Zilog Z80 chip, that weighs less than 2
pounds and is about the size of a letter-
sized paper pad. And on close inspec-
tion, you'll discover that the Z88’s
slightness doesn’t compromise its func-
tionality or compatibility.

Power is provided by four ordinary
AA batteries, which in the machine’s
unexpanded version give you about 20
hours of working time. The display is
an eight-line, 100-column supertwist
LCD. The Z88 uses solid-state storage,
with additional
memory capaci-
ty provided by
EPROM car-
tridges that fit
into slots on the

front of the
machine.
Even when

the screen dis-
play is switched
off, everything
held in the com-
puter’s memory
is maintained—
so long as the
batteries have
sufficient power.
The screen dis-
plays a warning
when the batter-
ies are getting
low, and an in-
ternal capacitor
will keep the
power going for up to six minutes while
you’re changing them. If you’re using
all three slots, however, you’ll have only
about 60 seconds to make the change.

= O

issue of PC Computing

Software is provided by an integrated
package called Pipedream, which incor-
porates word processing, spreadsheet,
and database capabilities. The machine
also comes with pop-up utilities, in-
cluding a clock, a calculator, a diary, an
organizer, and an alarm reminder.

The standard Qwerty keyboard in-
cludes a few unusual dedicated keys—
Index, Menu, Help, and a key marked
with a square and another with a dia-

Sir Clive’s Z88 road
machine—as light
and small as a book,
as wacky as its
inventor.

mond—that are linked to features of
the software.

Pressing the Index key returns the
user to the main command level of the
software and suspends the current op-
eration. The Help key gives context-
sensitive information about the current
operation. The Menu key lets the user
make selections regarding the current
application; each menu selection is dis-
played with a shortcut equivalent that
can be used in lieu of entering the full
command.

The square and diamond keys are the
prefix keystrokes for making shortcuts.
The square introduces a shortcut for
calling an application; the diamond pre-
cedes a shortcut for carrying out an
operation.

The keytoard is covered by a rubber
mat, which gives a dead feel to the keys
but insulates the machine from con-
tamination. It is virtually noiseless un-
less you activate the toggle to introduce
an audible click for each keystroke.

Another unusual feature of Pipe-
dream is its page-display map, which

..next page

cont'd from pg 8
The Final Solution

If you reduced the value of R12 as described above
and still don't get enough sensitivity with your
deck, and if the other “fixes” don't appeal to you,
your best bet is to add a linear amplifier to boost
the signal to the computer. Not much gain is needed,
so a single-transistor “class A" stage is all you
need, The circuit of Figure 2 is the answer that my
ZX81 “CE AMP" program came up with. It has a voltage
gain of about 3, and a P-P output swing of about 10
volts, Cost in parts is around $4, depending on how
much of the circuit you have in your junk box. On my
machine, ít allows most tapes to load reliably with

a volume setting anywhere between 4 and 10,

Wire it up on a 1"x1" piece of perf board, cut the
trace to the EAR jack (underside of board) and
connect the EAR jack to the input. Connect the
output to the left side of R12. Get the +15 volts
power for the circuit from the on-off switch (SW2),
the leg closest to the front edge of the board. A
good place to get the ground is from the grounding
strap soldered to the top of the video-section
enclosure. (If you want to get fancy, you can make
use of the expansion -port area. Al-top left is
ground, A2 is the EAR jack and B3 is the +15V
power.-ed.) The transistor can be virtually any NPN
silicon type capable of at least 200 mW. dissipation
and having a current gain (beta) of 50 or higher;
e.g. 2N3904, 2N4401, etc. (Beware of the Radio Shack
"2N 3904 grab-bag." These are, in my experience,

supplies, increase the gain to about 4 by making R1

= 1000 ohms, R4A = 75 ohms, R4B = 62 ohms. Cl and C3
should be 16V tantalum units, C2 may be an aluminum
electrolytic rated 3Y or up.

Load Amp for TS1000

You can use the one-transistor load amplifier
circuit with the ZX81/TS1000/TS1500 by making the
following changes in component values: *

R1 = 1000 ohms. R4B - not used * As for the 2068,

R2 = 4700 ohms Ci = 1 uF. Pre-wired boards
R3 = 160 ohms C2 - not used are available from
R4A = 33 ohms C3 = 3.3 uF.

the author for $6

These changes are necessary because of the different
supply voltage (9V instead of 15V) and input
resistor value (220 ohms instead of 1000 ohms) as
compared to the TS2068. Gain is set at about 3, and
P-P voltage swing is just under S volts.

If you're using fast-load routines such as Z-XLR8,
SDS, or Q-SAVE, it is recommended that you change
capacitor C11 (located near the MIC jack on the ZX81
board) from 47 nF. to 20-22 nF (.02-.022 uF.). This
increases the HF corner of the SAVE circuitry from
about 3,5 kHz. to over 7 kHz. and provides a
brighter signal. I did this simply by breaking the
existing capacitor in half horizontally, using a
pair of wire nips; works fine, but not a
“guaranteed” procedure. After doing this mod, I
found that I could run SDS (similar to Z-XLR8 at top

pretty lousy.)

Mount the board on top of the keyboard diodes (in
front of the keyboard connector) using sticky-foam;
watch for shorts. If you wish to use one of the
recorders with their 3V

little “Walkman"-type

EUROTECH

appears on the right side of the screen
and shows the layout of the whole page.
It allows you to start formatting a docu-
ment while you’re still in transit. If
you’re downloading to WordStar, it can
even retain print commands in a file af-
ter it’s been dumped to DOS.

At the end of a journey, the down-
loading procedures are simple and reli-
able, expedited via a cable using a 9-pin
RS-232 serial port and PC-Link II
communications software. The soft-
ware for the transfer resides in a 32K

The Z88’s biggest
attraction is its
price. The basic
machine costs
only $549.

EPROM cartridge in one of four Z88
slots and on a floppy on the target ma-
chine, which controls the download.
Not the least of the Z88’s attractions
is its low price. The basic machine costs
$549 in the United States, although for

this you get only 32K of memory. Ex-

pansion cartridges are available in 32K,
128K, and 512K packs, but a 512K car-
tridge together with a PC link will al-
most double the initial price. .

Sir Clive’s Z88 will be distributed in

=-

speed) even without a pre-conditioner.

So there you have it. That should wrap {t up, at
least from a hardware standpoint. In a future issue
we'll try to get you a flexible, variable fast-load

routine. 'Till then, "good loads, fair weather!"

the United States by Cambridge North
American, a subsidiary of Diversified
Foods, a $150-million-a-year Portland,
Maine, grocery wholesaler turned com-
puter distributor. Diversified took a
warning shot across the bow from Am-
strad as it lined up to use the Sinclair
name, which went legally to Amstrad
when Sir Clive sold the ZX line to the
company. Diversified finally agreed to
rechristen the venture. E
Cambridge North American hopes to
be moving the Z88 through computer
stores and major retail outlets offering
various promotional discounts. To help
the machine get off the ground in the
U.S. market, the company has signed a
letter of intent to acquire 51 percent of
its first dealer, Executive Computers, a
four-year-old laptop specialist in New
York City that sells to 800 of the For-

“tune 2,000 companies. | Al

FILE: 2XTMT<T.DNT
Silicon Mtn. Computers -
C-12, Mtn. Stn. Group Box
Nelson, EC VIL 2J3
Canada

November 1987

ZX-TERM*80 AND MEMOTEXT

This document details how you can "marry" the popular Memotext word-processor
with our 2X-TERM*80 terminal program for the 2X81/TS1000 computers. It details
how to up/download “raw" Memotext files, as well as how to upload text files
created with Memotext in an ASCII format readable by any computer.

Transferring "raw" files is quite simple, and would be useful for sending
entire sets of files to another 2X/TS user, either directly or via a BES or
other service. He could then view, edit, or print the files using Memotext.
However, such raw files would not be readable by other computer users; useful
if you want to maintain some degree of confidentiality. If you want your files
to be formatted, perhaps justified, and readable by anyone, you will have to
use the second approach (more complex, but not too difficult once you get the
hang of it).

I suggest that you first experiment with the "raw data" approach, perhaps with
the co-operation of another local ZX/TS user.

Regardless of which approach you use, the minimum hardware and scftware you
need are as follows:

HARDWARE :

2X81, TS1000 or TS1500 computer.

A suitable 48K or 64K RAM, with 8-1£K region disabled.
Modem (Byte-Back, or preferably Westridge)

Suitable static memory in 8-16K, as SCRAM, modified
“Hunter board", or "Delta Device".

M1* adaptor or modification.

Tape recorder or other mass-storage.

Printer and printer interface.

NAU AUN
oo oo 0 os

SOFTWARE :

Memotext, V3 (high memory version)
ZX-TERM*80

I no longer commercially supply Memotext V3. However, if you send $5 to cover
tape. photocopying and shipping, I’11 send you a copy on a "shareware" basis.
After you get it, send whatever you think it’s worth.

Silicon Mountain will of course supply the 2X-TERMx80 program, on either
cassette or EPROM. Write for details.

TRANSFERRING "RAW" MEMOTEXT FILES

To UPLOAD a set of Memotext files in Sinclair/Memotext format, proceed as
follows:

1: Set up your system.

2: LOAD Memotext V3, and configure it for your printer and interface. You

ae =

may optionally load the HELP! file. Create or load your files in the usual
way. If necessary, print them out to be sure they're as desired. (If the
files to be transferred already exist, even if created using a different.
version, you may skip this step.) Once your files are as you want them,”
save to tape using SAF (save all files).

3: Use the GIT function to exit Memotext, then enter NEW.

4: LOAD ZT-TERM*80, and confiqure for your printer interface if desired.
Relocate the program to 39024. After entering ZX-TERM*80, use ESCAPE (shift
space) to return to BASIC.

S: Re-enter Memotext at the cold boot entry point (RAND USR 43851). Re-LGAD
your prepared files using LAF (load ali files).

6: Aqain GIT from Memotext. Do not use RUN, CLEAR or NEW!

7: Re-enter ZX-TERM*80 with RAND USR 42622. Get the other person on the
line, and get ready to upload the files. When the other terminal is ready
to receive, ao to Xmodem with SHIFT 4. Press "U" for “upload.” Then answer
*U* for “variables.” The upload will commence.

8: When the transfer is complete, press any Key to return to the main loop
and terminate the connection.

Downloadina is very similar.
1: Set up your system.

2: LOAD Memotext V3, configure it for your printer, and optionally load the
HELP1 file.

3: QIT from Memotext, enter NEW, and LOAD 2X-TERMx80.

4: Get on-line, and prepare to download the file. Use SHIFT 4 to go to
Xmadem, followed by "D" for "download," and "U" for “variables.”

S: When the download is complete, return to the main loop and terminate the
connection. ESCAPE to BASIC, answering (N)o to "SAVE FILES?”

6: Re-enter Memotext at the warm boot (RAND USR 46555). You can now edit.
view, or print the files just downloaded.

TRANSFERRING FILES iN ASCII FORMAT

Usually you will want to transfer your text as ASCII files, formatted and
perhaps justified, in other words just as it would appear if you printed it
out. We have to take a somewhat different tack to accomplish this. What we
will essentially do is "fool" Memotext into thinking that it’s sending the
text file to the printer, when actually the translated and formatted file is
teing stored in *spare" memory. We will then use a short machine-code routine
to transfer the finished file into ZX-TERM*80’s DATA REM buffer, for uploading
to the other terminal.

Geing the other way, downloading an ASCII text file, is of course no problem
for ZX-TERM*80. If you relocate your “input buffer" as described, you can then
use the little "dump" routine installed at the original buffer location, to
send the file to your printer. i

Unfortunately, it isn’t feasible to convert such an ASCII file into Memotext
format. As a result, you won’t.be able to edit downloaded ASCII files. For

= 2 ~-

this reason, we will only discuss how to UPLOAD Memotext files in fully
formatted ASCII.

You will normally only transfer one text file at a time, though you could
strina several short text files together into a single upload. Also, data
files are not transferrable using this approach, unless their contents are
referred to within the text file. > i

To upload a Memotext file, follow these steps. As mentioned, it miaht seem
complicated at first: however, after some practise, you'll find it easier than
it first appears.

1-4: Follow steps i through 4 as for "raw" uploads. If the files to be
uploaded already exist on tape, you can omit steps 2 and 3.

5: After ZX-TERM*80 is installed, ESCAFE to BASIC and LOAD the originai
copy of Memotext. When asked for your interface type, answer "OTHER." Then
enter the following hexcode sequence:

ES2A32407723223240E1C9

This installs a new "printer driver” that sends the translated and
formatted ASCII output to memory instead of the printer, starting at the
location contained in SEED (more about that later).

6: When prompted for LF/CR options, answer “LF + CR." This is because most
boards want to see both a linefeed and a carriage-return code at the end of
every line. Don’t bother loading the HELP1 file; it would be overwritten
anyway.

7: After entering Memotext, load your file or files from tape (LTF or LAF).
NOTE: the length of your file or files to be sent in a single upload should
be less than around 12K. Remember, ZX-TERM*SQ’s DATA REM buffer is limited
to about 15K. In the process of translating, spaces: are added (when
justifying, indenting, etc.) and LF/CR codes are inserted after every line.
As a result, the ASCII translation will typically be somewhat longer than
the Memotext “source code.”

- HINT: set up your file for 40 or 40-column width, using (edit)W at the
beginning, for the convenience of other ZX-TERM*80 users.

8: QIT to BASIC, and enter RAND 50872. This sets the starting address for
the ASCII translation, and represents the first byte beyond Memotext’s data
area.

$: Re-enter Memotext at the warm boot (RAND USR 46555).

10: "Print" your text file to memory using PTF. Answer (Continuous mode.
Justify (Yes or (N)o as desired. After a few seconds, the program will be
back at the FUNCTION? prompt. Repeat for any other text files you wish to
send in this upload.

11: QIT to BASIC. Do not enter NEW. Instead, PRINT PEEK 16434+256*PEEK
16435. This will give the ENDING address of your translated file. If this
is a low number (below 506872), your text file(s) is/are too lona; the
“pointer* has wrapped around, and tried to print your file to the ROM. You
have to edit them down and repeat the procedure if this happens. Otherwise
you’ll crash when you try to import the file into the DATA REM buffer!

12: Without entering any other commands, re-enter ZX-TERM*80 with RAND USR
42622. Get into the main loop, and initialize your DATA REM using SHIFT 8.
ESCAPE back to BASIC using shift space, followed by (No in response to
"SAVE DATA?". 5 i

"Ss

13: Now comes the only tricky part. We have to enter a little machine-code
routine to transfer the file from high memory, into the DATA REM. You have |
to enter the following commands:

LET AS="EMRND::LEN : GOSUB PIVAL FAST AT LPRINT >:RND GOSUB :. GOSUB
?TRNDTAN"

LET A$(21)=CHR$ 83
LET A$(2Z)=CHRS118

Entering the first command is the one that will seem laborious at first. So
here’s a step-by-step procedure for entering this strange-looking command.
“sh*=SHIFT, *4n*= FUNCTION (shift ENTER), "“gr*=GRAPHIC (shift 9b.
“DEL"=DELETE (shift 0)

CHAR: KEYS USED

LET L

A -A

$ sh U

= sh L

A sh P

E E >
M M

END tn, T

: or, sh 1

: S, or

LEN fn, K

$ ar. J, ar
GCOSUB sh 3, H. sh 5, DEL, sh 8

PI fn, M

VAL tn. J

FAST sh F

AT fos, C

LFRINT sh S

) sh O i
: er, sh H, or

RNC fn, T

GOSUB sh 3, H, shS, DEL, sh 8

3 cr, K :

i

GOSUB sh 3, H, shS, DEL, sh 8
?

?

? ?
RND rs T
TAN tn, E
s sh P
ENTER

Enter PRINT. AS. It should look as shown above. Now enter the other two
commands listed above. Again PRINT A$; it should still look the same.

14: Now enter PRINT USR 32771. It should come back with 0. The file is now
in your DATA REM buffer!

15: Re-enter 2X-TERM*80 with RAND USR 42422. Use VU DATA (shift 5) ta
verify that the file has, indeed been translated, formatted, and moved into
the DATA REM. A

16: Upload the file as usual. SHIFT 4 gets you into Xmodem. Answer
CUdpload, then (P)rogram. And away it goes.

16: If you wish to save the translated file, truncated to its actual
lenath, you can of course do so by escaping, then answering (Y)es.to "SAVE

DATA?*. Pon

SPONSORED BY: PACIFIC COAST COMPUTER FAIR ASSOCIATION (A NON-PROFIT ORGANIZATION)

4407 31

NOILVZINV10d YOY NONI "3L0N

5231

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Cc
a

13IP09II( ssaippy I8xZ

23M00 a-—-17- OF D

JUL

The Vancouver Sinclair Users Group has been in existence since
1982. We are a support group for the owners and users of all
SINCLAIR and TIMEX computers.

Pres:- Gerd Breunung PH#(604) 931-5509
V/Pres:- Glenn Read

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Our membership dues are only $15.00/year and may be sent to
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Rod Humphreys
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